import numpy as np
import pandas as pd
arr1= np.arange(1,10).reshape(3,3)
df1=pd.DataFrame(arr1,columns=['a','b','c'])
df1.insert(0,"key",['001','003','002'])
print('第一个对象原始数据df1:\n',df1)
arr2=np.arange(10,14).reshape(2,2)
df2 = pd.DataFrame(arr2, columns=['a', 'e'])
df2.insert(0,'key',['001','004'])
print('第二个对象原始数据df2:\n',df2)
df3=pd.concat([df1,df2])
print('纵向外合并的数据df3:\n',df3)
df4=pd.concat([df1,df2],keys=['df1','df2'],sort=True)
print('纵向外和并,标记每个对象,并按行标签排序的数据df4:\n',df4)
df5=pd.concat([df1,df2],join='inner',ignore_index=True)
print('纵向内合并并重新设置连续行标签的数据df5:\n',df5)